一种面向多相开绕组电机的广义低次谐波电流抑制新方法

Medium-voltage multiphase open-end winding (OEW) motors and three-level multiphase H-bridge large-capacity inverters are the preferred solutions for large ship propulsion systems. However, OEW motor systems exhibit high-amplitude 3rd-, 5th-, and 7th-order harmonics (abbreviation “low-order harmonics”) current due to the H-bridge inverter PWM modulation dead zone and the motor’s nonideal magnetic field. Limited by the current loop bandwidth of the inverter with low switching frequency, it is difficult to suppress low-order harmonic currents with conventional methods. First, this article gives a 12-phase OEW induction motor (OEW-IM) mathematical model and its closed-loop control strategy. Second, combined with the phase characteristics of motor windings, a novel generalized low-order harmonic currents transformation matrix and its suppression method are proposed. The new method converts low-order harmonics into dc components by two sets of three-phase winding currents with a 30° phase difference and cooperates with a simple proportional–integral regulator to achieve closed-loop control. Moreover, the controller parameters for the proposed method are designed. Finally, the experiments are conducted to verify the proposed method under steady-state and dynamic conditions. The results show that the 3rd-, 5th-, and 7th-order current harmonics of the 12-phase motor system are reduced by over 70%. The proposed method is simple to implement and can be extended to other multiphase motor systems.